i always like to masturbate in front of a mirror. i can get very horny watching myself stroke my cock. i also like to get into a doggiestyle position and use my thumbs and forefingers of each hand to make a 'hole' i can stick my cock into, and watch it disappear as i pound my hands while i look behind at myself in the mirror. if you've got multiple mirrors, this could help, since you don't have to strain your neck, trying to look backwards. it's still fun though. i have examples of this in my gallery, and i'll include one here as well, so you can see what i'm talking about. i'm using lube in this photo, but i normally don't. all you have to do is prop one leg up on something, and go to it.
also, i love to gently rub and play with my balls.